Handle zlib compressed files

cmd/extract.go

@@ -1,9 +1,8 @@
 package cmd
 
 import (
-	"os"
-	"io"
 	"fmt"
+	"os"
 
 	"github.com/sector-f/jh_extract/nvc"
 )
@@ -33,24 +32,9 @@ func extractNVC(arcPath string, pathlist []string, outputDirectory string, extra
 	extractedCount := 0
 
 	for hash, nvcEntry := range entries {
-		switch nvcEntry.Flags {
-		case nvc.Uncompressed:
-			// Do nothing
-		case nvc.Compressed:
-			// TODO: Perform zlib decompression
-		default:
-			continue
-		}
-
 		_, exists := hashToPath[hash]
 		if extractUnknown || exists {
-			_, err = r.Seek(int64(nvcEntry.Offset), 0) // "0 means relative to the origin of the file"
-			if err != nil {
-				continue
-			}
-
-			data := make([]byte, nvcEntry.Length)
-			_, err = io.ReadFull(r, data)
+			data, err := nvcEntry.Data(r)
 			if err != nil {
 				continue
 			}

go.mod

@@ -2,8 +2,9 @@ module github.com/sector-f/jh_extract
 
 go 1.18
 
+require github.com/spf13/cobra v1.5.0
+
 require (
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
-	github.com/spf13/cobra v1.5.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 )

nvc/types.go

@@ -1,5 +1,11 @@
 package nvc
 
+import (
+	"compress/zlib"
+	"errors"
+	"io"
+)
+
 type EntryFlags uint32
 type Hash uint64
 
@@ -12,9 +18,38 @@ const (
 )
 
 type TocEntry struct {
-	Hash        Hash
-	Offset      uint32
-	RawLength   uint32 // Uncompressed length
-	Length      uint32 // Actual length in file
-	Flags       EntryFlags
+	Hash      Hash
+	Offset    uint32
+	RawLength uint32 // Uncompressed length
+	Length    uint32 // Actual length in file
+	Flags     EntryFlags
+}
+
+func (t TocEntry) Data(r io.ReadSeeker) ([]byte, error) {
+	_, err := r.Seek(int64(t.Offset), 0)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	var reader io.Reader = r
+
+	switch t.Flags {
+	case Uncompressed:
+		// Do nothing
+	case Compressed:
+		reader, err = zlib.NewReader(r)
+		if err != nil {
+			return []byte{}, err
+		}
+	default:
+		return []byte{}, errors.New("unsupported")
+	}
+
+	data := make([]byte, t.Length)
+	_, err = io.ReadFull(reader, data)
+	if err != nil {
+		return []byte{}, err
+	}
+
+	return data, nil
 }